How to extract numbers from a string in Python?

python regex string numbers
pablouche picture pablouche · Nov 27, 2010 · Viewed 1M times · Source

I would extract all the numbers contained in a string. Which is the better suited for the purpose, regular expressions or the isdigit() method?

Example:

line = "hello 12 hi 89"

Result:

[12, 89]

Answer

fmark picture fmark · Nov 27, 2010

If you only want to extract only positive integers, try the following:

>>> str = "h3110 23 cat 444.4 rabbit 11 2 dog"
>>> [int(s) for s in str.split() if s.isdigit()]
[23, 11, 2]

I would argue that this is better than the regex example because you don't need another module and it's more readable because you don't need to parse (and learn) the regex mini-language.

This will not recognize floats, negative integers, or integers in hexadecimal format. If you can't accept these limitations, jmnas's answer below will do the trick.

Related questions

Split string on whitespace in Python

I'm looking for the Python equivalent of String str = "many fancy word \nhello \thi"; String whiteSpaceRegex = "\\s"; String[] words = str.split(whiteSpaceRegex); ["many", "fancy", "word", "hello", "hi"]

Read More
Remove all special characters, punctuation and spaces from string

I need to remove all special characters, punctuation and spaces from a string so that I only have letters and numbers.

Read More
How to find all occurrences of a substring?

Python has string.find() and string.rfind() to get the index of a substring in a string. I'm wondering whether there is something like string.find_all() which can return all found indexes (not only the first from the beginning …

Read More